Environmental contaminants are natural or synthetic compounds that contaminate habitats and cause negative impacts on wildlife or plants. Notable examples include pesticides, heavy metals, fertilizers and radioisotopes. Amphibians are believed to be particularly susceptible to environmental contaminants because of their permeable skins, dependence on moist environments, and frequently biphasic lifecycles with obligate aquatic larval periods (Boone and Bridges 2003).

The effects of environmental contaminants on amphibians have only recently become the subject of intense study but the pace of this area of research has been great. Where negative effects of contaminants on amphibians have been found, the causal agents and amphibian responses have been diverse, including developmental malformations, reduced survival, reduced hatching success, delayed metamorphosis, or altered behavior. Some of these effects have been directly attributed to pesticides or other contaminants whereas other effects presumably result from indirect impacts of contaminants on aquatic algae or zooplankton.

Despite an abundance of studies demonstrating diverse impacts of environmental contaminants on individual amphibians and communities in laboratory and field-based studies, there is still some uncertainty regarding the role environmental contaminants play in amphibian population declines. Undoubtedly, environmental contaminants reduce populations or otherwise exacerbate ongoing declines in some regions and populations. However, this is one area in need of immediate additional study. For more information about environmental contaminants and amphibian declines, use our resource viewer below or see one of two recent reviews: Boone and Bridges (2003) and Bridges and Semlitsch (2005).